Airbag device and method for opening an airbag flap

ABSTRACT

An airbag device having at least one airbag flap having a first area which is used to cover an outlet for the airbag characterized in that the airbag flap is also provided with a second area upon which an airbag enfolding after release exerts a pressure, whereby the airbag flap performs a substantially rotary movement in order to free said outlet.

RELATED APPLICATION

[0001] This application is a continuation of International ApplicationPCT/EP02/09338, filed Aug. 21, 2002, the contents of which are hereincorporated by reference in their entirety. The benefits of 35 USC 120are claimed.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention concerns an airbag device and a method for openingan airbag flap, in particular, for use in a motor vehicle.

[0004] 2. Prior Art

[0005] Various airbag arrangements are known from the state of the art:

[0006] From DE 196 46 543, an interior trim part for motor vehicles withairbag equipment is known. In the release of the airbag, the cover areaof the guide channel is torn along its center line. The torn area opensin the form of a “pointed oval,” similar to the form of an open fishmouth.

[0007] From documents DE 100 01 040 C1, DE 38 43 686 A1, DE 40 22 881C2, and EP 0 940 300 A1, various other airbag covers are known that areflung inwards into the passenger space when the airbag is released,wherein the movement of the cover is limited by a restraining belt. Onecommon disadvantage here is that there is an injury risk when the coverenters the passenger space.

[0008] From EP 0 867 346 A1, an airbag device and a corresponding methodto release the airbag device are known, in which a cover of the exitopening of the airbag is essentially moved within an outside contour ofthe airbag device, or of a motor vehicle part containing the airbagdevice, when the airbag is released. This type of movement requires,however, an expensive guide bar bracket for the movement of the coverdevice within the outer contour.

SUMMARY OF THE INVENTION

[0009] The problem on which the invention is based, therefore, is tocreate an improved airbag device and an improved method to open anairbag flap.

[0010] The problem on which the invention is based is solved with thefeatures of the independent patent claims. Preferred embodiments of theinvention are indicated in the dependent patent claims.

[0011] A special advantage of the invention is to be found in that themovement of the airbag flap for freeing the exit opening of the airbagafter it is triggered proceeds, in a defined manner, essentially outsidethe passenger area of the motor vehicle. Thus there is an increasedsafety in comparison to the state of the art, since the opening airbagflap does not represent an injury risk for persons in the interior ofthe motor vehicle, in particular even if a front-seat passenger is in aso-called Out-Off Position, for example. The fact that the openingmovement of the airbag flap can essentially take place outside thepassenger space means that the danger of head injuries caused by theopening airbag flap is minimized, especially also in the Out-OffPosition.

[0012] Another special advantage of the invention is that the definedopening movement of the airbag flap can be obtained without a guide barbracket or the like, but rather with a rotary movement, for example,around an axis opposite the exit opening.

[0013] According to a preferred embodiment of the invention, two airbagflaps are provided that when closed form a space, tapering toward theexit opening, into which the airbag unfold inwards. With an unfolding ofthe airbag into this space, a pressure is exerted on both airbag flapsso that these rotary movements are effected in opposite turningdirections. In this way, the airbag flaps are displaced, at leastpartially, under an instrument panel, so that the airbag opening isfreed.

[0014] According to another preferred embodiment of the invention, anornamental cover is located on the airbag flap. A gap is providedbetween a boundary of the instrument panel and a boundary of the airbagflap, through which the ornamental cover extends, in a curved shape,onto the underside of the instrument panel. As a result of the curvedshape of the ornamental cover in its end area, its movement under theinstrument panel during the opening operation is assisted.

[0015] According to another preferred embodiment of the invention, theend area of the ornamental cover is fixed in a detachable manner on theinside of the instrument panel. This ensures that the ornamental coverretains the same visual appearance in the exit opening even with asubsiding clamping effect, for example, as a result of aging of thematerial. After triggering of the airbag, this connection is disengaged,for example, broken up.

[0016] According to another preferred embodiment of the invention, thereis a gap between the two airbag flaps when closed. Above this gap, theornamental cover has a breaking point. After the airbag is triggered,the corresponding pressure therefore acts directly on the breakingpoint, so that it can tear in a particularly easy way. The breakingpoint can be produced, for example, by weakening the material of theornamental cover, especially by means of a laser beam.

[0017] According to another preferred embodiment of the invention, theopposed rotary movements of the two airbag flaps are laterally limitedby the airbag housing. After the airbag is triggered, a stop is formedby the airbag flaps on the airbag housing. In this way, a defined endposition of the open airbag flaps exists outside the passenger space.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Below, preferred embodiments of the invention are explained inmore detail, with reference to the drawings. The figures show thefollowing:

[0019]FIG. 1, a first embodiment of an airbag device according to theinvention, when closed;

[0020]FIG. 2, the airbag device of FIG. 1, after release of the airbag;

[0021]FIG. 3, a second embodiment of an airbag device, according to theinvention, when closed and after the airbag is released;

[0022]FIG. 4, section A-A of FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0023]FIG. 1 shows an instrument panel 1 of a motor vehicle, inparticular, a private automobile. The instrument panel 1 has an exitopening for an airbag 2. The exit opening for the airbag 2 can also beprovided in another part of the interior trim of the motor vehicle.

[0024] The airbag 2 is located in a space delimited by, among otherthings, the airbag flaps 3 and 4. The space delimited by the airbagflaps 3 and 4 tapers in the direction of the exit opening and is, forexample, shaped essentially in the form of a funnel.

[0025] The airbag flap 3 has an area 5 for covering one side of the exitopening. Furthermore, the airbag flap 3 has an area 6 that forms aboundary of the space tapering in the direction of the exit opening.Correspondingly, the airbag flap 4 has an area 7 covering the other sideof the exit opening and an area 8 that delimits the tapering space onthe other side.

[0026] The areas 6 and 8 of the airbag flaps 3 and 4 run toward oneanother in the direction of the exit opening, but without touching.Between the areas 6 and 8, therefore, a gap also remains directly on theexit opening. Above this gap, there is a breaking point 9 of anornamental cover 10. The breaking point 9 is, for example, produced bymeans of a laser weakening of the ornamental cover 10.

[0027] The ornamental cover 10 extends over the entire range of the exitopening and is firmly connected with the areas 5 and 7 of the airbagflaps 3 and 4.

[0028] The ornamental cover 10 has end areas 11 and 12. The end area 11is conducted through a gap, found between the edge of the instrumentpanel 1 and the edge of the area 5, on the back side of the instrumentpanel 1. In this way, the end area 11 obtains a curved shape. On theunderside of the instrument panel 1, the end area 11 is fixed, in adetachable manner, with a fastening element 13 on the underside of theinstrument panel 1. The fastening element 13 may be, for example, a clipconnection or a plastic bolt.

[0029] Correspondingly, the end area 12 is conducted through the gapformed between the edge of the area 7 and the edge of the instrumentpanel 1 to the back side of the instrument panel 1, and is fixed with afastening element 14 on the back side of the instrument panel 1.

[0030] The airbag flap 3 is located on a joint 15 that enables apivoting movement of the airbag flap 3 in the direction of the arrow 16when the airbag is released. The joint 15 is located opposite the exitopening of the airbag.

[0031] Correspondingly, the airbag flap 4 is located on a joint 17 thatpermits a pivoting movement in the direction of the arrow 18 uponrelease. The joint 17 is also located opposite the exit opening of theairbag.

[0032] The airbag device of FIG. 1 also has a housing with two lateralhousing parts 19 and 20. The rotary movement of the airbag flap 3 in thedirection of the arrow 16 is limited by a stop formed by the housingpart 19 upon release, just as the corresponding movement of the airbagflap 4 is limited by a stop formed by the housing part 20. Thecorresponding stops are thereby formed by the area 6 and area 8,respectively, of the airbag flaps 3 or 4.

[0033] A gas generator 22 for deployment of the airbag 2 upon release islocated in a lower area 21 of the airbag device.

[0034]FIG. 2 shows the airbag device of FIG. 1 after release of theairbag. Elements of FIG. 2 that correspond to elements of FIG. 1 aredesignated with the same reference symbols.

[0035] In the representation of FIG. 2, airbag 2 has been releasedbecause the gas generator 2 [sic; 22] suddenly produced a gas for theexpansion of the airbag 2. By the inflowing of gas into the airbag 2, apressure is produced, in the airbag in the areas 6 and 8 of the airbagflaps 3 and 4 (see FIG. 1). A pressure was likewise produced in this wayat the breaking point 9.

[0036] In this way, the breaking point 9 of the ornamental cover 10 (seeFIG. 1) was broken so that the ornamental cover 10 was subdivided intothe two areas 23 and 24. By the expansion pressure of the airbag 2, theairbag flaps 3 and 4 effect a pivoting movement in the direction of thearrow 16 or 18 (see FIG. 1), and then form stops with their areas 6 and8 against the housing parts 19 and 20 in the end position shown in FIG.2.

[0037] The areas 5 and 7 of the airbag flaps 3 and 4 have moved underthe respective edges of the instrument panel 1, together with the areas24 and 23 of the ornamental cover, with this opening movement, in theprocess of which the fastening elements 13 and 14 (see FIG. 1) weredetached—that is, were broken, for example. The moving under wasassisted by the curved shape of the end areas 11 and 12 of theornamental cover 10. In addition, along with the movement under theinstrument panel 1 there may be an elastic deformation of the instrumentpanel 1 as a result of the squeezing effect of the airbag flaps 3 and 4moving under the instrument panel 1.

[0038] It is particularly advantageous in this connection that theopening movement of the airbag flaps 3 and 4 proceed essentially outsidethe passenger space. In this way, the injury risk to the automobilepassengers is diminished. In addition, it is particularly advantageousthat this movement be implemented without an expensive guide bar bracketor the like, essentially only by means of a pivoting movement around thejoints 15 and 17.

[0039] In the embodiment shown, however, the airbag flaps 3 and 4initially penetrate the interior space of the motor vehicle by a smallamount with the opening movement after triggering of the airbag, and arethen almost completely withdrawn again from the interior space of theautomobile as they move under the instrument panel. The reason for thishas to do with the curvature radii of the envelope of the instrumentpanel and the opening movement. This slight penetration into thepassenger space is not an impairment to the safety of the passengers ofthe motor vehicle, however. Accordingly, embodiments with only oneairbag flap, and/or another part of the interior trim of the motorvehicle instead of the instrument panel, can be implemented.

[0040] The invention has the additional advantage that, for example, ajamming of the opening airbag flap in a guide bar bracket can beavoided. The process of deploying the airbag therefore, is effectedaccording to a precisely pre-specified movement course and at the sametime is implemented by means of a second pivoting movement. It is alsoparticularly advantageous that the pivoting movement requires only arelatively small fraction of the pressure delivered by the gas generator22, so that the expansion of the airbag 2 is not substantially sloweddown or a particularly large gas generator 22 would be required.

[0041]FIG. 3 shows a second embodiment of an airbag device, accordingthe invention. In the embodiment of FIG. 3, elements which correspond toFIGS. 1 and 2 are again designated with the same reference symbols.

[0042] The embodiment of FIG. 3 essentially differs from the embodimentof FIGS. 1 and 2 in that the areas 6 and 8 of the airbag flaps areformed to run straight in sections. Even with this embodiment, however,the space circumscribed by areas 6 and 8 tapers in the direction of theexit opening of the airbag 2.

[0043] The opened position is shown with a broken line in FIG. 3.

[0044]FIG. 4 shows the section A-A of FIG. 3. As can be seen in thisdepiction, the joint 15 is designed as a hinge. The ornamental cover 10is connected in a form-locking manner with the area 5 of the airbag flap3 (by means of fastening element 25).

Reference Symbol List

[0045] (1) Instrument panel

[0046] (2) Airbag

[0047] (3) Airbag flap

[0048] (4) Airbag flap

[0049] (5) Area

[0050] (6) Area

[0051] (7) Area

[0052] (8) Area

[0053] (9) Breaking point

[0054] (10) Ornamental cover

[0055] (11) End area

[0056] (12) End area

[0057] (13) Fastening element

[0058] (14) Fastening element

[0059] (15) Joint

[0060] (16) Direction of arrow

[0061] (17) Joint

[0062] (18) Direction of arrow

[0063] (19) Housing part

[0064] (20) Housing part

[0065] (21) Lower area

[0066] (22) Gas generator

[0067] (23) Area

[0068] (24) Area

[0069] (25) Fastening elements

What is claimed is:
 1. Airbag device with a first and a second airbagflap (3, 4), with the following features: a) the airbag flaps (3, 4)each have a first area (5, 7) to cover an exit opening of an airbag (2);b) the airbag flaps (3, 4) each have a second area (6, 8), bordering thespace to hold the airbag (2) that tapers toward the exit opening whenthe airbag flaps (3, 4) is closed; c) other ends of the second areas (6,8) of the airbag flaps (3, 4), which are remote from the exit opening,are supported on a joint (15, 17); d) the airbag (2) exerts a pressureon the second areas (6, 8) of the airbag flaps (3, 4) after thetriggering of the airbag during deployment, so that the airbag flaps (3,4) effects an essentially rotary movement (16, 18) around the joints(15, 17) to free the exit opening; e) at least a part of the first areas(5, 7) of the airbag flaps (3, 4) can be pushed under an instrumentpanel (1) or another part of interior trim of the motor vehicle when theairbag (2) is released, as the result of the essentially rotarymovement.
 2. Airbag device according to claim 1, in which the firstareas of the airbag flaps have an ornamental cover (10), and theornamental cover together with the first areas (5, 7) are pushed, atleast in part, under an instrument panel (1) or another part of theinterior trim of a motor vehicle during release of the airbag.
 3. Airbagdevice according to claim 2, which when closed forms a gap between aboundary of the first areas (5, 7) and a boundary of the instrumentpanel (1), and end areas (11, 12) of the ornamental cover (10) runthrough the gap to the back side of the instrumental panel (1) or thepart of the interior trim of the motor vehicle.
 4. Airbag deviceaccording to claim 3, in which the end areas of the ornamental cover(10) have a curve-shaped profile on the sides facing the edges of theinstrument panel, in order to assist moving the first areas, togetherwith the ornamental cover (10), under the edges of the instrument panel,or under the other part of the interior trim of the motor vehicle, aftera triggering of the airbag.
 5. Airbag device according to claim 1 with asecond airbag flap (4) is constructed such that the second airbag flap(4) can essentially effect a rotary movement (18), in a directionopposed the rotatory movement (16) of the first airbag flap (3) to freethe exit opening.
 6. Airbag device according to claim 1, in which thespace is designed essentially in the shape of a funnel.
 7. Airbag deviceaccording to claim 1, in which a gap remains between the first area ofthe first airbag flap (3) and the first area of the second airbag flap(4) when closed, and a breaking point of an ornamental cover (10),covering the first area of the first airbag flap and the first area ofthe second airbag flap, is located over the gap.
 8. Airbag deviceaccording to claim 1, with a housing (19, 20) to hold the airbag flapsso that the rotary movement of the first airbag flap is limited by astop on the housing.
 9. Method to open airbag flaps, which have firstareas to cover an exit opening of the airbag, and second areas on whichan airbag deploying after a triggering exerts a pressure, wherein aspace to hold the airbag, tapering toward the exit opening when theairbag flaps are closed, is formed by the second areas, with thefollowing steps: triggering of the airbag; exertion of a pressure on thesecond area of the airbag flaps by the deploying airbag; effecting arotary movement of the airbag flaps to free the exit opening.
 10. Methodaccording to claim 9, wherein the rotary movement is effected around anaxis which lies at one of the ends of the second areas remote from theexit opening.
 11. Method according to claim 9, wherein the first areasare pushed, at least in part, under an instrument panel or another partof interior trim of the motor vehicle during release of the airbag. 12.Method according to claim 9, wherein an ornamental cover of the firstareas is also pushed under the instrument panel.
 13. Method according toclaim 9, wherein the airbag deploys into the space after the airbag istriggered, so that the airbag flaps effect essentially rotary movementsin opposite directions to free the exit opening.
 14. Method according toclaim 13, wherein a gap remains between the airbag flaps when closed,and the ornamental cover, running above the first areas, has a breakingpoint above the gap so that after the airbag is triggered, theornamental cover is separated by the pressure of the deploying airbag onthe breaking point.
 15. Method according to claim 9, wherein themovement of at least the first airbag flap is limited by an airbaghousing.
 16. Method according to claim 9, wherein the ornamental coveris connected in an end area with an underside of the instrument panel,in a detachable manner, so that after the triggering of the airbag thedetachable connection is broken so that the ornamental cover, togetherwith the first area, is pushed at least in part under the instrumentpanel or a part of the interior trim of the motor vehicle.
 17. Methodaccording to claim 9, in which the movement of at least the first airbagflap proceeds essentially outside the passenger space, after the airbagis triggered.